KINETICS OF DEGRADATION OF PARABENS 5O5 1 1.0 10.0 9.0 8.0 7.0 6.0 5.0 ..... I I I I I 0.04 0.08 0.12 0.16 0.20 TOTAL PHOSPHATE, moles/liter Figu"e 5. Effect of phosphate concentration on the rate of hydrolysis of ethyl paraben at 70 ø C, pH 8.24, and ionic strength 0.6 parabens underg•o general base catalysis, and that hydroxyl ion is not the only species which can catalyze their hydrolysis. ( Received October 25, 1973) REFERENCES (1) Aalto, T. R., Fi•Tnan, M. C., and Rigler, N. E., Uses, antibacterial and antifungal studies, properties and determination, J. Amer. Pharm. Ass., Sci. Ed., 42, 449-57 (1953). (2) Pekkarinen, L., and Tomrolla, E., Hydrolysis of alkyl salicy]ate in alkaline solutions, Acta Chem. Scand., 13, 1019-30 (1959). (3) Shou, A. S., and Frauch, P., Untersuchungen iiber die stabilitSt von p-aminobenzoe- s•iure-methylester bei kiinstlicher alterung, Pharm. Acta Helv., 34, 37-52 (1959). (4) Ravel, N. N., and Parrott, E. L., Hydrolysis of methyparaben, 1. Pharm. Sci., 56, 274-5 (1967). (5) Littlejohn, O. M., and Husa, W. J., The potentizing effect of antimolding agents in syrups, ]. Amer. Pharm. Ass., Sci. Ed., 44, 305-8 (1955).

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